Homework.

So Many Choices

Starting With The Right Solvent Is The Best Way To Avoid A Costly Mistake

November 23, 1996|By Edward R. Lipinski, New York Times News Service.

A solvent is a substance, usually liquid, that will dissolve another substance. All do-it-yourselfers buy and use a number of solvents. Some are used for cleaning, others for use as paint, shellac or varnish thinners.

Choosing the right solvent can make a job easier; using the wrong one can damage tools or a work project.

To avoid costly mistakes, the do-it-yourselfer should be familiar with the most useful solvents and where, when and how to use them. Turpentine is one of the few solvents not made from petroleum distillates. It is produced by distilling the oleoresins from pine trees. It is also known as spirits of turpentine or simply turps. The best grade is called pure gum spirits of turpentine.

Turpentine has more solvency than mineral spirits. Care should be taken when using it to thin oil-or alkyd-based paints; otherwise the paint could be overthinned, which can cause it to run or drip. Even though turpentine is less toxic than petroleum-based solvents, it can still cause an allergic reaction in some individuals.

Mineral spirits, also called "white spirits" (trade names include Varnolene and Texaco spirits), is a petroleum distillate specifically manufactured as a substitute for turpentine. Most painters prefer it as a paint thinner because it costs less, is not so sticky and has a less offensive odor than turpentine.

Both turpentine and mineral spirits are good brush cleaners, although turpentine can remove paint that has hardened slightly. Mineral spirits will dissolve only paint that is still fresh.

Naphtha is a petroleum solvent similar to mineral spirits but with a greater volatility; it is used chiefly as a paint thinner or a cleaning agent. Naphtha is a more powerful solvent than mineral spirits, so less is needed to thin the same amount of paint. But it also makes paint dry faster and may make it difficult to blend strokes or brush out drips.

Naphtha is highly flammable; when using it, work in a well-ventilated area -- out-of-doors, if possible -- and wear rubber gloves and a respiratory mask. Some furniture refinishers use naphtha to remove accumulations of wax on furniture. It can quickly dissolve wax layers, but naphtha can also penetrate through the wax and seep under veneer. There it will dissolve the glue, causing the veneer to loosen and pop up.

Alcohol is sold in many forms: isopropyl, methyl, wood, ethyl and denatured alcohol. Isopropyl alcohol is the familiar rubbing alcohol and is formulated for external medicinal use. It is also useful for removing resinous stains on clothing and for removing the gummy tar residue on ashtrays.

Methyl alcohol is a dangerously toxic solvent not suitable for home use. (The liquid and vapors can have a destructive effect on the optic nerve.) It is also called wood alcohol or methanol.

Denatured alcohol is used for thinning shellac and for cleaning brushes used to apply shellac. It can also be used to remove light pencil marks on wood. Cooks will find that it is a good fuel for the small burner under a fondue pot or chafing-dish.

Lacquer thinner is a blended mixture of two or more solvents. Acetone, amyl or ethyl acetate, keotone and toluene are common ingredients in lacquer thinners. Obviously, lacquer thinners are designed to thin lacquers and clean brushes and spray equipment used for lacquer finishing.

But lacquer thinner is also an effective brush cleaner. It can soften and dissolve most paints even after they've hardened.

Acetone, a common ingredient in lacquer thinner, is a useful solvent for anyone who works with plastics. It is effective in removing residue from plastic cements, especially the cyanoacrylates (also called instant or super glues). It is the recommended thinner for polyester resins and fiberglass, and it is also useful for cleaning tools and equipment used for working with these materials.

Acetone and lacquer thinner are useful for removing paint and varnish stains on clothing made of natural fibers, but they will soften and dissolve many plastics and some synthetic fabrics. Do not use a nylon brush for applying these solvents because the acetone may attack the bristles. Both acetone and lacquer thinner are highly flammable, and both release toxic fumes, so avoid inhaling for any length of time.

Methylene chloride is the principal ingredient in most paint removers and in heavy-duty brush cleaners. Sometimes it is combined with other ingredients and sold as "graffiti remover." It is effective in removing all finishes, but it attacks and softens plastics. It can also be hard on human skin, so wear rubber gloves when working with it.

Obviously, most chemical solvents are flammable and release toxic fumes. Be sure to read the manufacturers' instructions before using them and observe all safety precautions. Buy them in limited quantities -- only as much as you need -- and store them in metal containers away from children, pets and flames.